Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> writes:
> On Thu, 14 Apr 2016, Felipe Balbi wrote:
>
>> >> --- a/drivers/usb/storage/scsiglue.c
>> >> +++ b/drivers/usb/storage/scsiglue.c
>> >> @@ -127,6 +127,11 @@ static int slave_configure(struct scsi_device *sdev)
>> >> if (queue_max_hw_sectors(sdev->request_queue) > max_sectors)
>> >> blk_queue_max_hw_sectors(sdev->request_queue,
>> >> max_sectors);
>> >> + } else if (us->pusb_dev->speed >= USB_SPEED_SUPER) {
>> >> + /* USB3 devices will be limited to 2048 sectors. This gives us
>> >> + * better throughput on most devices.
>> >> + */
>> >> + blk_queue_max_hw_sectors(sdev->request_queue, 2048);
>> >> } else if (sdev->type == TYPE_TAPE) {
>> >> /* Tapes need much higher max_sector limits, so just
>> >> * raise it to the maximum possible (4 GB / 512) and
>> >
>> > Argh! This has the same kind of problem as before. What will happen
>> > when somebody has a USB-3 tape drive?
>>
>> I didn't know that was even plausible :-) Anyway, I'll update, but while
>> at that, so I use for bcdUSB instead of speed as Oliver suggested ? I
>> mean, a USB3 stick running on high-speed can also support 2048 max
>> sectors, right ?
>>
>> let me know
>
> To tell the truth, I have no idea. There probably aren't enough USB-3
> products in existence yet to tell -- not to mention that with the
> existing code, we wouldn't detect any exceptions.
>
> It sounds reasonable... But won't a USB-3 device running at high speed
> provide a device descriptor that has bcdUSB set to 0x0210? (See the
> second paragraph of section 9.6.1 in the USB-3.1 spec.)
right, but an HS USB 2.1 device is also recent enough that it's likely
to work similarly, no ?
--
balbi
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